Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSFORD2004MUSTANG BASE, 2D COUPE, 3.9 6, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 146 (MODULE COMMUNICATIONS NETWORK)SYSTEM TESTSTEST D: AUXILIARY POWERTRAIN CONTROL MODULE DOES NOT RESPOND TO SCAN TOOL
2004 Ford Mustang Base, 2D Coupe, 3.9 6, Automatic
Test D: Auxiliary Powertrain Control Module Does Not Respond To Scan Tool
2004 Ford Mustang Base, 2D Coupe, 3.9 6, AutomaticSECTION Test D: Auxiliary Powertrain Control Module Does Not Respond To Scan Tool
WARNING: This page is about a different car, the 2002 Ford RV Cutaway, 2002 Ford Econoline, 2002 Ford E450 Super Duty, and 2002 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
This test applies only to vehicles equipped with diesel engines.
- Turn ignition switch to OFF position. Disconnect Auxiliary PCM (APCM) Black 4-pin harness connector C2176, located below left side of instrument panel. Inspect connector for loose, damaged or corroded terminals. If connector is okay, go to next step. If connector is faulty, repair connector as necessary. Retest system operation.
- Measure resistance of Tan/Orange wire between DLC terminal No. 2 and APCM Black 4-pin harness connector C2176 terminal No. 1. See Figure and Fig 1 . Measure resistance of Pink/Light Blue wire between DLC terminal No. 10 and APCM Black 4-pin harness connector C2176 terminal No. 3. If both resistances are less than 5 ohms, replace APCM. Retest system operation. If either resistance is 5 ohms or more, repair open in Tan/Orange wire and/or Pink/Light Blue wire between APCM Black 4-pin harness connector C2176 and DLC. Retest system operation.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.